2011 GSXR 750 huge flat spot 4-7k rpms

2011 GSXR 750, Danos ECU flash, full hindle ti exhaust, kn filter, pair valve delete, exhaust servo delete.

Took the bike up the street the other day, and at about 4000 rpms it falls flat on its face for a sec or 2, then takes off like a bat out of hell about 7000.

I realize on the track, i would almost never be at that low of rpms, but still, something is not right.

Danos said definitely not the ECU flash, but idk.

Google is limited with info...possible TPS sensor?

 

Is it throwing any codes ?

 

No

 

Did it run correctly before the flash and other changes? I have Dano's flash on my '14 with similar similar specs and it runs fine throughout the rpm range. Try the b mode?

 

Honestly don't know....I bought the bike during the winter, sounded fine, but never rode it, and built it into a race bike.

The bike revs fine while on the stand, banging through the gears. I'll tear it down this wknd to make sure i did the pair valve delete correctly....clean TPS contacts, etc....If that doesn't work, i'll swap out throttle bodies on my '12 750 street bike that runs great and see what that does.
I'll try changing modes as well.

Does have new plugs.

Thanks

 

You could swap the ECU if you suspect the flash. And eliminate that variable. Would be the quickest also.

 

2011 and 2012 ECU's are surprisingly different.

 

Didnt realize that.

 

Connectors/plugs are different. I didnt know either til i tried swapping th 11 and 12 during the build process

 

So no one has seen it run that can attest it was running perfectly before 'x'? If not, start with the easy stuff first - how old is the fuel? Flush it. Pull the plugs and look for the obvious signs of getting no fuel or too much fuel.

PAIR valve removal shouldn't have any effect on running condition unless the bike's tune still utilizes an o2 sensor that is reading exhaust oxygen content.

Oh, and obviously check all the stuff you touched last. I had a similar problem with a 675 (never rode it, built it over the winter, had a weird stumble then it would scream up top). Turns out when I put the throttle bodies back on I folded one of the rubber couplers over enough that it was blocking fuel flow from the injector. Stupid mistake I wouldn't have thought to double check. I only caught it because I was thinking the fuel was bad and it had clogged hte injectors from sitting over the winter. And when I pulled the airbox and opened the throttle bodies I saw a big piece of rubber folded over.

 

The bike was a wrecked bike. It sounded fine on the stands, running through the gears, with a full yosh system, and pc5 but i never rode the bike.

Fast forward to the Danos ECU flash and QS, full Hindle exhaust, fresh plugs (and gapped), Pair valve delete, fresh 93 gas and bike stumbles, spits and sputters.

I just came in from garage.....Took airbox off, checked the pair valve delete hoses and plugs, connectors, etc...Didn't see anything.

With bike on stand, 2nd gear, 40 mph, 4000 rpm's....I slowly roll the throttle on and it just stumbles, cracks. pops, and revs won't increase...I continue to roll throttle on and eventually revs will climb and sound normal.

With bike in neutral (no load), i can crack the throttle to 12,000 rpms and sounds perfect. No stumbles at all.

I bought a used TPS but i'll have to pull the TB's partially to swap it out.

I'll probably buy an '11 ECU and put the stock pipe on it and see how it does.

 

Fuel pump or dirty tea bag?

 

Bike threw an F1 code on start up this morning. Turned it off. Grabbed a jumper wire, started bike and F1 light disappeared and no codes showing now. So something is triggering a code at startup. I can't replicate as of now. I'll wait til later today to see if it'll throw the code again. Jumper wire is still attached so hopefully i can catch a code.f

-Also when i started it this morning, and it warmed up, fan kicked on around 130 but then shut off.. Which isn't right. I know the Danos flash is supposed to kick fan on around 190. Hmmm, makes me wonder if i have a bad flash.

It generally idles on the rough side. RPM's bouncing a round a bit but eventually will smooth out once warm.

Like i said, if i twist throttle from idle, it'll rev hard and fast to 12-13k. No stutters, stumbles, nothing. If i hold throttle at 4k or so rpm and then try to increase rpm's it will stumble, so bad that i can continue to turn throttle 1/4 turn more and revs won't increase but eventually the revs take off fast, like a light switch.

 

Ok, so let's think about this a bit. Without getting off into the weeds, looking at the things that were modified the Q/S or ECU flash are the only items that could be causing this kind of issue. It's extremely unlikely the tune is so rich/lean that it's causing this. The Q/S however could certainly be. If for some reason the Q/S is getting a false signal (is the pedal vibrating or something that could be setting it off?) it would be cutting spark completely which would result in exactly what you're describing.

So first I'd do the obvious and just unplug the Q/S and see if the problem persists.

Second would be to determine which cylinder or cylinders are misfiring when the issue actually happens. I typically use a thermometer on the headers and you'll see a big delta pretty quickly if one is misfiring. Then start moving coils from the cold cylinder and see if the problem follows the cylinder or the coil.

If the misfire isn't just one cylinder or it moves around from one to the other and isn't consistent then certainly check things like clogged/dirty fuel injectors or fuel filters.

Also regarding the TPS, can you verify the calibration of the one you have before you just swap it out?

 

I appreciate your tips and info....I'll do what you recommend in the morning. I used my thermo gun at Jennings a couple years ago when my RSV4 went into 'urgent service' mode on the back stretch...Limped it in. Put the gun on each header and one was 'cold' so to speak. Ended up being coil wire got pinched between tank and frame and rubbed a bare spot in the wire. Fixed at track and all was good.

As far as the TPS goes, not sure i can calibrate or verify it.

 

The bike didn't throw a code today....Shot each header with thermo gun, all reading similar temps.
Bike actually seemed to be running/idling better, although i didn't ride it.

 

I captured the F1 code this morning....C65....GOOGLE says it may have something to do with the clutch switch.
I have removed the left hand switches but do still have the 2 clutch wires at the clutch lever. The clutch wire harness has been pared down to the 2 clutch wires and i still use the oem connector to the main wiring harness.

I copied this :

"It case you didn't get an answer. A C65 is an out of range idle speed. It should only show up if the throttle is closed and the engine idle is outside the 1200-1400 rpm range (too low or too high). I've also have seen this code appear when an aftermarket clutch lever is installed the the clutch switch is not properly engaged by the lever. When the clutch lever is pulled, the switch cause the ECU to switch to a neutral gear fuel map, and when the clutch is released, the switch notifies the ECU to switch to the gear fuel mapping."

 

Well shit, i think i need the pair valve eliminator plug.....I believe this is the plug for the pair valve solenoid. EDIT: Danos flash disables the pair valve function in the ECU.

I

The yellow plug on the left is the pared down clutch harness. The 2 wires go to the clutch switch on the perch.

Woodcraft ignition eliminator on the right.

I'm gonna put on another clutch perch/wiring harness.

 

So i finally got around to working on this.

Bought a TPS for the TB's...no luck.

Bought a used set of TB's with all sensors, 'allegedly' 2000 miles on them, swapped them out, no luck.

Put new TPS on new TB's, no luck. Switched and swapped sensors, double/triple checked all connectors, fuel pump priming, etc...no luck.

I've taken many many tanks off of GSXR's over the years and there is very minimal fuel leakage that comes out of the fuel pump line when disconnected...But the tank on the 750 that i'm having trouble with, would continue to drain out of the fuel line. This was not normal.

So i took the tank off my '12 GSXR 600 race bike and put it on the 750, and whala, purrs like a kitten. Sounds great, smooth like normal.

Hot damn.

 

BINGO

Is the fuel pump rebuildable? Hate to buy a used one for what they're going for on ebay.